1. Field of the Invention
The present invention relates to an exposure apparatus, a manufacturing system, and a device manufacturing method.
2. Description of the Related Art
In the lithography process for manufacturing devices such as semiconductor devices, a photoresist, for example, is applied on the surface of a substrate and the photoresist is exposed to light to transfer patterns from a mask to the photoresist using light and electronic beams. The photoresist on which the patterns have been transferred is developed to form patterns on an oxide film, nitride film, or metal film on the substrate. In the process, a coater is used for applying the photoresist, an exposure apparatus is used for exposing the photoresist, and a developer is used for developing the photoresist. The exposure apparatus performs the exposure process on the substrate divided into areas of a certain size by, for example, step-and-repeat or step-and-scan exposure. Each of the divided areas is subjected to one exposure step or one exposure scan and is called a shot region.
In order to ensure that the line width of the circuit pattern ultimately formed on the substrate falls within a predetermined tolerance with respect to a design value, the line width of the resist pattern resulting from the lithography process must be within a predetermined tolerance. One factor that influences the line width of a resist pattern is the dose of light with which the photoresist is irradiated.
In order to provide a resist pattern having a desired line width, the resist pattern must be exposed with an appropriate dose of light. The appropriate dose of light depends on the sensitivity of the photoresist. The sensitivity of a photoresist varies depending on the waiting time between the application of the photoresist onto the substrate and the exposure of the photoresist (pre-exposure waiting time). The sensitivity of the photoresist also varies depending on the waiting time between the exposure of the photoresist on the substrate and the development of the photoresist (post-exposure waiting time).
In the conventional lithography process, variations in the pre-exposure waiting time and post-exposure waiting time have caused variations in resolution line width.
In a technique disclosed in Japanese Patent Laid-Open No. 10-261572, the dose of light is calculated by taking into account the time between the application of a photoresist onto a substrate and the start of the exposure of the substrate and the calculated dose of light is used to perform the exposure. In the technique disclosed in Japanese Patent Laid-Open No. 10-261572, the time between the start of exposure of the substrate and the development of the substrate is also taken into account to calculate the dose of light, and the calculated dose of light is used to perform the exposure.
Also in the technique disclosed in Japanese Patent Laid-Open No. 10-261572, the time between the application of a photoresist onto the substrate and the start of exposure of the substrate is used as the pre-exposure waiting time for the substrate for calculating the dose of light. In the technique disclosed in Japanese Patent Laid-Open No. 10-261572, the time between the start of exposure of the substrate and the development of the substrate is used as the post-exposure waiting time for the substrate for calculating the dose of light. That is, the same dose of light is used for multiple shot regions on one substrate.
However, pre-exposure waiting time and post-exposure waiting time vary among the multiple shot regions on one substrate. Accordingly, using the same dose of light for the multiple shot regions can cause variations in the line width of a resist pattern formed by the exposure and the development on the substrate among shot regions.